Add switchable theme to tuner

Allows option in tuner to switch between system theme overlays
if multiple exist. Requires a restart to take effect.

Test: Settings -> Tuner -> Other -> Theme
Change-Id: Iea43b9cbb67fd91c6008be594ad4cfd19c3f57ec
diff --git a/packages/SystemUI/AndroidManifest.xml b/packages/SystemUI/AndroidManifest.xml
index e07d865..0b5383a 100644
--- a/packages/SystemUI/AndroidManifest.xml
+++ b/packages/SystemUI/AndroidManifest.xml
@@ -171,6 +171,8 @@
     <!-- shortcut manager -->
     <uses-permission android:name="android.permission.RESET_SHORTCUT_MANAGER_THROTTLING" />
 
+    <uses-permission android:name="android.permission.MODIFY_THEME_OVERLAY" />
+
     <application
         android:name=".SystemUIApplication"
         android:persistent="true"